Method of forming acid-resistant printing-designs.



UNITED STATES PATENT OFFICE.

GEORGE R. CORNWALL, OF PORT CHESTER, AND HERMAN O. BOEDICKER, OF NEW YORK, N. Y ASSIGNORS, BY MESNE ASSIGNMENTS, TO HARRY O. CORNWALL, OF WYOMING, NEYVJERSEY.

METHOD OF FORMING ACID-RESISTANT PRINTING-DESIGNS.-

SPECIFICATION forming part of Letters Patent No. 643,892, dated February 20, 1900.

Application filed January 14,1898. Serial No. 666,697. (Nospeoimens) T0 ctZZ whom, it may concern.-

Be it known that we, GEORGE R. CORN- WALL, residing at Port Chester, in the county of Westchester, and HERMAN O. BoEDIcKnR, residing at New York, in the county of New York, State of New York, citizens of the United States, haveinvented certain new and useful Improvements in Methods of Forming Acid-Resistant Printing-Designs, of which the following is a specification.

This invention relates to an improved method of forming acid resistant printing-designs. It is intended particularly for use in surface printing; and its object is to produce a design which will be resistant to the action of strong cleaning or etching agents, such as nitric or other acid. Our process may also be and preferably is carried out in such a manner as to render the design resistant to the action of turpentine and similar solvents, as well as that of nitric acid, so that the use of turpentine in reinoving ink from the design will not affect the design itself.

Our invention is particularly adapted for use in printing with aluminium plates, inasmuch as it is especially desirable to use nitric acid from time to time in cleaning such plates.

The completed design when formed according to our invention consists of asphalt or equivalent material, which is capable of resisting the action of strong acids. In order to enable it to resist also the action of turpentine, we prefer to employ what is known as sensitive asphalt and after the design has been formed therewith to expose it to the action of light, so as to convert it into a form or condition in which it is more resistant to acid and is comparatively insoluble in turpentine.

Printing-designs for use in surface printing have been formed with asphalt by photographic processes, and designs formed in fatty ink have been strengthened by covering them with asphalt; but the materials generally used in laying down, drawing, or transferring printing-designs-such as crayon,tuche,trans fer or printing ink, or albuminous or gelatinous mediumsare readily attacked by acid. On the other hand, the use of such acid has been found to be necessary from time to time to clean the plate. The aforesaid mediums have also the disadvantage that being more or less plastic they tend to spread or flatten under the compressing action of printing. Asphalt being resistant both to the action of acids and to mechanical pressure is therefore a superior medium for the printing-design; but for obvious reasons it cannot be conveniently used directly in forming the design by drawing or mechanical transfer, and the process of photographic transfer is not conveniently applicable to most classes of work on account of its slowness and complication.

Our process enables the con version of a design formed of any of the aforesaid destructible mediums-such as crayon,tnche, transfer-ink, or printing inkinto a comparatively insoluble or resistant state, and it consists, in effect, in the substantial replacement of the destructible design material by an indestructible material, such as asphalt. For this purpose the plate, preferably of aluminium, which has had the design formed thereon in crayon, ink, or other usual ink-attracting medium, is first treated with a solution of gum-arable or similar gumming-up material, preferably a gum-arabic solution of the thickness of cream containing sixty (60) drops of glycerin to an ounce of gum. This gum adheres to all parts of the plate except where it is covered by the design, and the plate being then dried a film of gum is left on those parts of the plate, such film being Water-attracting andink-rejecting in its nature. The plate is then treated with turpentine or other suitable solvent or softener for the greasy or fatty matter of the crayon or ink, and the material constituting the design having been thus loosened and largely dissolved is wiped ofi with a soft dry cloth, leaving the space or outline occupied by the design substantially or apparently clean. Inasmuch, however, as the plate on which the design has been formed has the usual property of a lithographic plate of absorbing or retaining a trace or residue of the fatty or greasy design material in its surface, the removal of the material of the design in this manner is not complete, a film orimpregnation of fatty material still existing in all parts of the plate originally covered by the design. The excess or surplus of fatty design material, however, which projects above the surface on which it is applied, is substantially removed. In order to effect this purpose, it is necessary that the solvent used should so loosen the ink or fatty material of the design that it can be readily wiped off. We speak of a liquid having the property of thus facilitating the removal of the design as a solvent, although in some cases it might actually dissolve o nl y a small part of the material, and the word solvent is therefore intended to include any liquid which is capable of softening or loosening the design material in this manner. Furthermore, it is necessary that this solvent should be of a nature to be attracted by the design and to be rejected by the gum, and it is therefore as a matter of course non-aqueous. The plate having been wiped clean and dry and free from all dissolved or loosened material, a thin solution of asphalt is flowed or floated over the plate, and the latter is again dried, leaving a film of asphalt over the whole surface of the plate, including the part originally covered by the design. For this purpose we prefer to use what is known as sensitive asphalt, which is readily acted upon by light, and thereby converted into a comparatively resistant and insoluble form. The sensitive asphalt is dissolved in any suitable solvent-such as naphtha, benzole, or preferably chloroformsufticient of the solvent being used to form a thin solution, which is applied to the plate as above described. The plate having been well dried is then soaked in water, which has the eifect of loosening up or softening the gum under the asphalt, and the plate being then wiped 0% the asphalt comes 01f from all surfaces except those originally covered by the design, where it still adheres strongly. This leaves a design on the plate in asphalt exactly corresponding to the original design. The form is the same, but the material has been changed so as to be comparatively resistant to the action of acids and also is much harder than the ink, crayon, or tuche originally used in making the design, and is therefore better adapted to resist the wear and tear of the printingoperations. Itbeingunderstoodthat a sensitive asphalt is preferably used in the above-described process, the process is completed by the exposure of the design to light. This changes the nature of the asphalt and renders it more resistant to nitric acid and also comparatively resistant to the action of turpentine,so that nitric acid can be used in clean ing the plate and the turpentine can be used in removing the ink from the plate at any time without in either case injurying the design. As regards the immunity of the design from the action of nitric acid it will be seen that there is a special advantage in the application of this process to aluminium -plate printing, inasmuch as aluminium itself is not attacked by nitric acid, whereas other surface-printing materials, such as lithographic stone and zinc, are attacked by such acid. An aluminium plate with a design formed thereon by the above process can be treated with nitric acid repeatedly and, in fact, almost indefinitely without deterioration or injury of either the plate or the design.

The object of adding glycerin to the gumming-up solution is to enable the resulting film to retain or attract moisture more readily,

and thereby facilitate access of water and more rapidly loosen up the asphalt.

In rendering an albumen or gelatin design insoluble or resistant the design is first rolled up with a greasy ink and is then treated by the method above described, so as to change the ink design into an asphalt design. The

albumen or gelatin design in this case probably remains on the plate, but is so covered by the asphalt as to be protected.

Having thus described our invention, what we claim as new, and desire to secure by Letters Patent, is

l. The method of forming an acid-resistant design which consists in forming upon a plate a design in a material which is soluble in a non-aqueous solvent, applying to the parts of the plate not covered by the design a film of water-attracting material, removing the surplus material of said design down to the surface of the plate by its non-aqueous solvent, applying to the plate a non-aqueous solution of a hard acid-resistant material, drying the plate and applying water thereto.

2. The method of converting an acid-destructible printing-design into an acid-resistant design, which consists in applying to the parts of the printing-plate not covered by the design, a film of water-attracting material, then removing so much of the material of the design as projects above the surface on which it was formed, then applying to the plate a solution of asphalt in a non-aqueous solvent, drying the plate and exposing it to the action of water.

3. The method of converting an acid-destructible printing-design into an acid-resistant design which consists in applying to the parts of the plate not covered by the design a film of water-attracting material, then removing the surplus material of the design, applying to the plate a solution of sensitive asphalt in a suitable solvent, drying the plate, soaking it in water, whereby the asphalt is left only on the parts covered'by the original design and finally exposing the design to the action of light so as to convert the asphalt into a comparatively insoluble and resistant form.

4-. The method of forming a printing-design which is resistant to nitric acid and to turpentine, which consists in forming on a plate a design in ink attracting material which is removable by a non-aqueous solvent, applying to the parts of the plate not covered by the design a film of water-attractplate a solution of gum and Water, drying the plate, removing the surplus material of the design with turpentine, applying to the plate a solution of sensitive asphaltin a non-aqueous solvent, drying the plate, soaking it in water and thereby removing the asphalt from the parts covered by the gum, and exposing the asphalt design to the action of light.

GEO. R. CORNWALL. H. O. BOEDIOKER.

Witnesses:

HARRY E. KNIGHT, M. V. BIDGOOD. 

